This invention pertains to a system for recharging an aquifer for shallow wells and means for operating the system.
Aquifers of shallow or moderate depth are a common source of water used for irrigation and sometimes for municipal water systems. These aquifers are often found in broad flat flood plains of slow running rivers. It would be expected that the river would recharge the aquifer. However, the river beds of such rivers are frequently silted tightly so that the water does not seep into the aquifer. Then, the aquifer is recharged only when the river is at flood stage or by rain water or snow melt.
In order to provide for any other recharging of the aquifer it is necessary to remove or by-pass the siltation. The common means for recharging is to dig a large pit down to the level of the aquifer, then to fill the pit with gravel and filter sand and then to pump water from the river into the pit. However, the silt from the river water again soon fills the filter sand with silt which again blocks the water from flowing through the filter sand and the recharging pit is again ineffective. It is then necessary to dry the pit and replace the sand.
By my invention I provide a system of recharging the aquifer by use of wells or a trench dug into the aquifer. The opening is lined, preferably with a plastic membrane, and then filled with pea gravel and covered with filter sand.
I also provide novel means for lining the trench and cleaning the filter bed. By shaping the recharging area with a narrow trench into the aquifer and a broad filter bed it is possible to provide for lower siltation and easy cleaning of that bed by my novel means.